1. Field of the Invention
This invention generally relates to an angular rate sensor, and in particular, relates to an angular rate sensor having an oscillator.
2. Description of the Related Art
An angular sensor is a sensor detecting an angular rate during a revolution, and is used for a device avoiding a camera shake, a system such as car navigation system, a vehicle, and an attitude control system of a robot. A tuning-fork oscillator having arms on the base thereof is used for an oscillator of an angular rate sensor. In the angular rate sensor having the oscillator, oscillation of the oscillator is transmitted outside through other components. And the oscillation is changed in a case where the angular rate sensor is mounted on a system. As a result, the property of the oscillator is changed. And an external oscillation influences the oscillation of the oscillator. Therefore, an output of the angular rate sensor is changed because of the oscillation during a running of a vehicle. This possibly causes a malfunction of the system.
A following art is disclosed in order to reduce a leakage of the oscillation of the oscillator or an influence of the external oscillation to the oscillator. Japanese Patent Application Publication No. 2000-292173 (hereinafter referred to as Document 1) discloses an art where an oscillation absorption member fixes a groove portion having U shape and a supporting metal, the groove portion and the supporting metal being provided on a ceramics portion of a tuning-fork oscillator composed of a piezoelectric device and the ceramics portion. Japanese Patent Application Publication No. 9-203638 (hereinafter referred to as Document 2) discloses an art where a tuning-fork oscillator is mounted on a substrate and both ends of the substrate are fixed with an oscillation absorption portion. Japanese Patent Application Publication No. 8-178669 (hereinafter referred to as Document 3) discloses an art where a base surrounding a tuning-fork oscillator is provided and the both ends of the base is fixed with an oscillation absorption portion.
In a case where the tuning-fork oscillator oscillates in a direction vertical to a face therefore, a member (a ceramics portion in Document 1, a support substrate in Document 2 and a base in Document 3) supporting the oscillator oscillates so that a counter balance is achieved, in the arts in accordance with the Document 1 through Document 3. In Document 1 through Document 3, a member of which amplitude is large holds a member supporting the oscillator. It is difficult to restrain a leakage of the oscillation of the oscillator and an influence of the external oscillation to the oscillator.